The objective of the research proposed here is to develop new and general methods for constructing complex unsaturated azacyclic systems. It is our view, that the new vinylsilane chemistry proposed here will allow a number of complex systems to be constructed with an efficiency and stereoselectivty heretofore impossible. The specific objective of the first phase of our research is to define sufficiently the scope stereochemistry, and limitations of iminium ion-vinylsilane cyclizations such that this reaction can be rationally used for the preparation of complex bioactive materials. Specific total syntheses of the alkaloids deplancheine, geissoschizine, ajmalicine, and ajmaline, the Elaeocarpus alkaloids elaeokanines-A and -B, and the Amaryllidaceae alkaloid elwesine are proposed. Our aim is that by developing efficient synthetic entries to azacyclic systems of these types, and by developing the chemistry of vinylsilanes as cyclization terminators, that promising pharmacological leads can in the future be rapidly developed with this chemistry with potential therapeutic implications.